The present invention relates to a portable telephone and, particularly, to a portable telephone having an external memory unit connector and hence capable of connecting to an external detachable memory unit via the connecting unit.
Recently, portable telephones have spread that enable not only speech communication but also text mail communication. As for the text mail communication, received mails, transmission mails, etc. are memorized in a readable and writable memory unit that is mounted on an internal printed circuit board of a portable telephone together with data such as received dates and sender information. When a user wants to display information of a mail or the like on a display means, he performs predetermined manipulations on a manipulation means, whereupon sender information etc. of the mail or the like is displayed.
If a user wants to keep a received mail, he can keep it forever in the portable telephone by designating it as a mail to be kept. Portable telephones of the type concerned have a function of displaying a list of dates, senders (receivers), titles and the like, when a user want refer to reception transmission mails.
A portable telephone with a memory card is disclosed in Japanese Patent Laid-Open No. 2000-32169 as a portable telephone having a detachable memory unit.
In this portable telephone with a memory card, a user can check the contents of a conversation later by mounting a detachable memory card in the portable telephone and recording, in the memory card, what the user and the counterpart say during the conversation using the portable telephone. With this function, even if the user switches portable telephones, he need not do re-registration work if he makes switching to a proper memory card.
However, it is expected that in the future employment of color display means and provision of high-speed communication services will increase mails having a relatively large data amount such as mails containing a photograph or a moving picture whereas text-only mails will also be exchanged. In such a situation, a heavier load will be imposed on the memory unit for memorizing transmitted or received mail information and the number of pieces of information that can be memorized will becomes very small.
Large-capacity memory unit are physically voluminous and expensive. Portable telephones incorporating a large-capacity memory unit are expensive to users who mainly exchange text mails though they are acceptable to users who send and receive mails having a large amount of information.
Conversely, for users who frequently send and receive mails containing such data as a moving picture, a portable telephone incorporating a small-capacity memory unit is difficult to use because the memory unit becomes full of information in a short time.
Where a portable telephone enables use of only a non-detachable memory unit, the only method for transferring data of a photograph, a moving picture, or the like to another electronic device is to perform data communication via a cable. This is inconvenient; that is, this takes time and is cumbersome.
The technique of the publication No. 2000-32169 is merely intended to memorize what the user and the counterpart say during a conversation using a portable telephone and later check the contents of the conversation, as well as to dispense with telephone number re-registration work by switching memory cards in switching portable telephones used. The portable telephone disclosed in this publication is not valuable to both kinds of users who send and receive mails having a large amount of data and users who mainly exchange text mails.